Cellulose fibers, typically cotton, are widely used for clothes and products of fibers because of their many advantages such as high hygroscopicity and good feel. Products of cellulose fibers are soiled with oil, sebum, mud or the like due to the use and wearing and are cleaned by laundry for re-use. However, such dirt is likely to cling to cellulose fibers and products thereof and can not be easily removed by laundry. Consequently, this leads to disadvantages of stain, black smear, discolored smudge, etc. which reduce the value of clothes and the like. For this reason, a need exists for products of cellulose fibers having improved dirt-removing property (dirt removability). Dirt does not easily come off by laundry from cotton and the like which readily absorb oily and aqueous substances. So far, products of cotton free from said problem have not been found.
In such current situation, it has been proposed to attach polyvinyl alcohol as a laundry size to products of cellulose fibers. The proposed method contemplates causing the dirt to adhere to polyvinyl alcohol so that the dirt is separated, together with polyvinyl alcohol, from the product of cellulose fibers by laundry. However, the method can achieve this effect only once, and necessitates depositing polyvinyl alcohol on a product of cellulose fibers every time the product is washed. Thus the method can not be said to be means for improving dirt removability.
On the other hand, polyester, nylon and other synthetic fibers are extensively used for their numerous advantages such as high mechanical properties, chemical resistance and ease of care, but have a drawback of tending to permit accumulation of static electricity. Various antistatic agents have been used to overcome the drawback, but substantially all of them come off during laundry and are merely temporarily effective.
For practical use as clothes, products of synthetic fibers should be imparted laundry durability as well as antistatic property. As a method of giving antistatic property to a product of synthetic fibers, it is known to coat synthetic fibers with a hydrophilic polymer having double bonds by radical polymerization (Japanese Examined Patent Publication No.40,554/1985).
However, a fully crosslinked polymer needs to be formed to produce a coating film having the required washing resistance from a hydrophilic polymer. The radical polymerization of a hydrophilic polymer with double bonds for conversion to a crosslinked polymer entails a disadvantage of essentially using an ethyleneimine derivative, i.e. a highly toxic crosslinking agent or a volatile, highly toxic acrylic acid.
Said conventional procedure makes it difficult to maintain hygiene and healthy working environment, and needs special apparatus. Therefore the procedure has not been a useful technique in an ordinary processing plant which is intended to use mainly open-type equipment. Further a serious problem has been posed in that products of synthetic fibers should be subjected to a washing process of considerable scale to make the product of synthetic fibers non-skin irritable.
The accumulation of static electricity described above is due to the inherent hydrophobicity of synthetic fiber resins. The hydrophobicity of synthetic fiber resins raises another disadvantage that dirt is firmly held by products of synthetic fibers. In other words, dirt, for example, oily dirt such as oil grime and lipstick smudge is not easily removed from clothes of synthetic fibers and will not easily come off by washing. Unavoidably the dirt remains on products of synthetic fibers. However, no technique has been developed to improve the dirt removability of synthetic fiber products and to prevent dirt from permanently sticking to synthetic fiber products.